<!DOCTYPE html>
<html lang="en">
	<head>
		<title>three.js webgl - morph targets</title>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
		<link type="text/css" rel="stylesheet" href="main.css">
	</head>

	<body>
		<div id="container"></div>
		<div id="info">
			<a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> - morph targets<br/>
			by <a href="https://discoverthreejs.com/" target="_blank" rel="noopener">Discover three.js</a>
		</div>

		<script type="importmap">
			{
				"imports": {
					"three": "../build/three.module.js",
					"three/addons/": "./jsm/"
				}
			}
		</script>

		<script type="module">

			import * as THREE from 'three';

			import { GUI } from 'three/addons/libs/lil-gui.module.min.js';
			import { OrbitControls } from 'three/addons/controls/OrbitControls.js';

			let container, camera, scene, renderer, mesh;

			init();

			function init() {

				container = document.getElementById( 'container' );

				scene = new THREE.Scene();
				scene.background = new THREE.Color( 0x8FBCD4 );

				camera = new THREE.PerspectiveCamera( 45, window.innerWidth / window.innerHeight, 1, 20 );
				camera.position.z = 10;
				scene.add( camera );

				scene.add( new THREE.AmbientLight( 0x8FBCD4, 1.5 ) );

				const pointLight = new THREE.PointLight( 0xffffff, 200 );
				camera.add( pointLight );

				const geometry = createGeometry();

				const material = new THREE.MeshPhongMaterial( {
					color: 0xff0000,
					flatShading: true
				} );

				mesh = new THREE.Mesh( geometry, material );
				scene.add( mesh );

				initGUI();

				renderer = new THREE.WebGLRenderer( { antialias: true } );
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( window.innerWidth, window.innerHeight );
				renderer.setAnimationLoop( function () {

					renderer.render( scene, camera );

				} );
				container.appendChild( renderer.domElement );

				const controls = new OrbitControls( camera, renderer.domElement );
				controls.enableZoom = false;

				window.addEventListener( 'resize', onWindowResize );

			}

			function createGeometry() {

				const geometry = new THREE.BoxGeometry( 2, 2, 2, 32, 32, 32 );

				// create an empty array to  hold targets for the attribute we want to morph
				// morphing positions and normals is supported
				geometry.morphAttributes.position = [];

				// the original positions of the cube's vertices
				const positionAttribute = geometry.attributes.position;

				// for the first morph target we'll move the cube's vertices onto the surface of a sphere
				const spherePositions = [];

				// for the second morph target, we'll twist the cubes vertices
				const twistPositions = [];
				const direction = new THREE.Vector3( 1, 0, 0 );
				const vertex = new THREE.Vector3();

				for ( let i = 0; i < positionAttribute.count; i ++ ) {

					const x = positionAttribute.getX( i );
					const y = positionAttribute.getY( i );
					const z = positionAttribute.getZ( i );

					spherePositions.push(

						x * Math.sqrt( 1 - ( y * y / 2 ) - ( z * z / 2 ) + ( y * y * z * z / 3 ) ),
						y * Math.sqrt( 1 - ( z * z / 2 ) - ( x * x / 2 ) + ( z * z * x * x / 3 ) ),
						z * Math.sqrt( 1 - ( x * x / 2 ) - ( y * y / 2 ) + ( x * x * y * y / 3 ) )

					);

					// stretch along the x-axis so we can see the twist better
					vertex.set( x * 2, y, z );

					vertex.applyAxisAngle( direction, Math.PI * x / 2 ).toArray( twistPositions, twistPositions.length );

				}

				// add the spherical positions as the first morph target
				geometry.morphAttributes.position[ 0 ] = new THREE.Float32BufferAttribute( spherePositions, 3 );

				// add the twisted positions as the second morph target
				geometry.morphAttributes.position[ 1 ] = new THREE.Float32BufferAttribute( twistPositions, 3 );

				return geometry;

			}

			function initGUI() {

				// Set up dat.GUI to control targets
				const params = {
					Spherify: 0,
					Twist: 0,
				};
				const gui = new GUI( { title: 'Morph Targets' } );

				gui.add( params, 'Spherify', 0, 1, 0.01 ).onChange( function ( value ) {

					mesh.morphTargetInfluences[ 0 ] = value;

				} );
				gui.add( params, 'Twist', 0, 1, 0.01 ).onChange( function ( value ) {

					mesh.morphTargetInfluences[ 1 ] = value;

				} );

			}

			function onWindowResize() {

				camera.aspect = window.innerWidth / window.innerHeight;
				camera.updateProjectionMatrix();

				renderer.setSize( window.innerWidth, window.innerHeight );

			}

		</script>

	</body>
</html>
